Tougher times for Drug Resistant Bacteria

The Secret of how to prevent bacteria from developing drug resistance has been revealed in a new study.Drugs called bisphosphonates, widely prescribed for bone loss has been found to help in preventing an enzyme that helps in conjugation of bacteria, by help of which it derives drug resistance.

Many highly-drug resistant bacteria rely on an enzyme, called DNA relaxase, to obtain and pass on their resistance genes. Relaxase  plays a crucial role in conjugation as it is the gate keeper that starts and stops the movement of DNA between bacteria durig conjugation.

researchers at the University of North Carolina at Chapel Hill, have stopped the microbes’ ability to spread, among other advantageous mutations, resistance to antibiotics, by disabling the enzyme using molecules known as  bisphosphonates

The study by Matthew Redinbo and his associates is published in this week’s Proceedings of the National Academy of Sciences USA

The antibiotic-resistant Escherichia coli bacteria that were trying to pass their genes along, actually died when their DNA relaxase was shielded thus preveinting the spread of drug resistant bacteria andpossibility of more mutations.

The news is will bring fresh hopes at a stage when drugresistant strain of the bacteria Staphylococcus aureus infects over 1 million US hospital patients every year.

Advertisements

Microarray based Bio Detection Technologies

DNA microarray detection of antimicrobial resistance genes in diverse bacteria

Study published at http://cat.inist.fr/?aModele=afficheN&cpsidt=17459830
High throughput genotyping is essential for studying the spread of multiple antimicrobial resistance. A test oligonucleotide microarray designed to detect 94 antimicrobial resistance genes was constructed and successfully used to identify antimicrobial resistance genes in control strains. The microarray was then used to assay 51 distantly related bacteria, including Gram-negative and Gram-positive isolates, resulting in the identification of 61 different antimicrobial resistance genes in these bacteria. These results were consistent with their known gene content and resistance phenotypes. Microarray results were confirmed by polymerase chain reaction and Southern blot analysis. These results demonstrate that this approach could be used to construct a microarray to detect all sequenced antimicrobial resistance genes in nearly all bacteria.

Genetically Guided Treatment For Cancer

Two critical characteristics of breast cancer that are important to treatment can be identified by measuring gene expression in the tumor, a research team led by scientists at The University of Texas M. D. Anderson Cancer Center reports in Lancet Oncology online.

Researchers developed and validated a new genomic microarray test that identifies whether a tumor’s growth is fueled by the female hormone estrogen and the role of a growth factor receptor known as HER-2 that makes a tumor vulnerable to a specific drug.

“This is one important step towards personalized diagnosis and treatment planning based on an integrated genomic test of an individual tumor,” said senior author W. Fraser Symmans, M.D., associate professor in the M. D. Anderson Department of Pathology.

The Lancet Oncology paper results are the latest in an effort by the research team to develop a single test to quickly and efficiently determine the characteristics and vulnerabilities of a patient’s breast cancer and ultimately to guide treatment.

About 70 percent of breast cancers are estrogen-receptor positive and another 15 to 25 percent are human epidermal growth factor receptor-2 (HER-2) positive. Each receptor status requires different types of treatment.

“This moves us closer to developing an integrated single genomic test that could estimate the risk of cancer relapse after surgery, determine the ER and HER2 receptor status, and also gauge the sensitivity of the tumor to hormone therapy and chemotherapy,” says Lajos Pusztai, M.D., Ph.D., associate professor in the M. D. Anderson Department of Breast Medical Oncology, and team leader with Symmans.

Last fall, the group published a study showing that a genomic microarray test can also predict a patient’s response to chemotherapy. They also presented a paper in December showing that another genomic index predicts how an ER-positive patient will respond to hormonal therapy.

The study was funded by the National Cancer Institute, the Breast Cancer Research Foundation and the Goodwin Foundation.

Co-authors with Symmans and Pusztai are: first author Yun Gong, M.D., and Nour Sneige, M.D., of the M. D. Anderson Department of Pathology; Kai Yan, Keith Anderson, and Kenneth Hess, of the M. D. Anderson Department of Biostatistics; Feng Lin, M.D., Vicente Valero, M.D., Daniel Booser, M.D., Jaime Mejia, M.D., and Gabriel Hortobagyi, M.D., of the M. D. Anderson Department of Breast Medical Oncology; Christos Sotiriou, M.D., Ph.D., Institut Jules Bordet, Brussels, Belgium; Fabrice Andre, M.D., of Institut Gustave Roussy, Villejuif, France; Frankie Holmes, M.D., John Pippen Jr., M.D., and Svetislava Vukelja, M.D., of U.S. Oncology-Texas Oncology; Henry Gomez, M.D., of the Instituto Nacional de Enfermedades Neoplasicas, Lima, Peru; and Luis Barajas, M.D., Departmento de Ginecologia Oncologica, Instituto Mexicano del Seguro Social, Guadalajara, Mexico.

Contact: Scott Merville
University of Texas M. D. Anderson Cancer Center

The Insider -Code inside Codes : Scientists Discover Parallel Codes in Genes

Researchers from The Weizmann Institute of Science report the discovery of two new properties of the genetic code. Their work, which appears online in Genome Research, shows that the genetic code—used by organisms as diverse as reef coral, termites, and humans—is nearly optimal for encoding signals of any length in parallel to sequences that code for proteins. In addition, they report that the genetic code is organized so efficiently that when the cellular machinery misses a beat during protein synthesis, the process is promptly halted before energy and resources are wasted.

DNA sequences that code for proteins need to convey, in addition to the protein-coding information, several different signals at the same time. These “parallel codes” include binding sequences for regulatory and structural proteins, signals for splicing, and RNA secondary structure. Here, we show that the universal genetic code can efficiently carry arbitrary parallel codes much better than the vast majority of other possible genetic codes. This property is related to the identity of the stop codons. We find that the ability to support parallel codes is strongly tied to another useful property of the genetic code—minimization of the effects of frame-shift translation errors. Whereas many of the known regulatory codes reside in nontranslated regions of the genome, the present findings suggest that protein-coding regions can readily carry abundant additional information.

“Our findings open the possibility that genes can carry additional, currently unknown codes,” explains Dr. Uri Alon, principal investigator on the project. “These findings point at possible selection forces that may have shaped the universal genetic code.”

The genetic code consists of 61 codons—tri-nucleotide sequences of DNA—that encode 20 amino acids, the building blocks of proteins. In addition, three codons signal the cellular machinery to stop protein synthesis after a full-length protein is built.

While the best-known function of genes is to code for proteins, the DNA sequences of genes also harbor signals for folding, organization, regulation, and splicing. These DNA sequences are typically a bit longer: from four to 150 or more nucleotides in length.

 

DNA Analysis Could Boost Accuracy Of Thyroid Tests

Source: http://www.medicalnewstoday.com/sections/genetics/

By fine-tuning “fine-needle aspiration” biopsies with a super-fast genetic microarray technology, a team of surgeons from NewYork-Presbyterian Hospital/Weill Cornell Medical Center in New York City says they can greatly enhance the accuracy of these tests.

“For patients with worrisome thyroid nodules, this means better information on whether the nodule is malignant or benign. That should help them and their doctors make better decisions as to what treatment they’d like to pursue,” explains senior researcher Dr. Thomas J. Fahey III, associate professor of surgery and Frank Glenn Faculty Scholar in Surgery at Weill Cornell Medical College, and associate attending surgeon at NewYork-Presbyterian Hospital/Weill Cornell Medial Center in New York City.

In the study, the team created microarray-generated “gene expression profiles” from fine-needle aspirates by comparing the expression of thousands of genes from both cancerous and benign thyroid tissues. This process ended in a grouping of 25 differently expressed genes that helped distinguish malignant from benign growths.

“We next tested the accuracy of these patterns using 22 fine-needle aspirate samples from benign or malignant thyroid nodules,” Dr. Lubitz explained.

“In all but one case, the microarray test agreed completely with the results of extensive histological analysis in the lab,” she said.

According to the researchers, a move from histological to microarray analysis of thyroid aspirates could impact anywhere from 5 to 25 percent of patients undergoing this kind of diagnosis — giving them a better grasp of whether they might require surgery, for example.

Cost remains a factor, with a single microarray screen currently totaling about $500. “We anticipate, however, that as this technology becomes more widespread and improves, the price per test will fall much lower,” Dr. Fahey says.

microarray for transgenomics studies and Study of Evolution of organisms

Barcode microarrayshas demosntrated the various ways in which the microarrays can be used in various ways.Though mirred in controvesy as any new technology has been subjected in its infancy, the basic principles behind the technology can be put to use in many other frontiers. It may be optimized to study transgenomics organims and its evolution. To study the development of drug resistance bacteria and virus. To find out how microbes evolve though all this may require new approaches it all could stem from the basic principles adopted by DNA microarry and barcode microarray and SNP arrays

%d bloggers like this: